Seeding machine with seed delivery system

ABSTRACT

A seed delivery system for use in a seeding or planting machine that removes the seed from a seed meter by capturing the seed therefrom. The delivery system then moves the seed down to a lower discharge point and accelerates the seed horizontally rearward to a speed approximately equal to the forward travel speed of the seeding machine such that the seed, when discharged has a low or zero horizontal velocity relative to the ground. Rolling of the seed in the trench is thus reduced. Furthermore, as the seed only has a short drop from the outlet to the bottom of the seed trench, the seed has little vertical speed to induce bounce. The delivery system uses a brush belt to capture, move and accelerate the seed. By capturing the seed and moving it from the meter to the discharge, the seed is held in place relative to other seeds and the planter row unit. As a result, the seeds are isolated from row unit dynamics thereby maintaining seed spacing.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/616,877, filed Feb. 9, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/504,801, filed Oct. 2, 2014 and issued as U.S.Pat. No. 9,686,905 on Jun. 27, 2017, which is a continuation of U.S.patent application Ser. No. 12/364,010, filed Feb. 2, 2009 and issued asU.S. Pat. No. 8,850,995 on Oct. 7, 2014, the disclosures of which arehereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to a seeding machine having a seed metering systemand a seed delivery system for delivering seed from the meter to theground.

BACKGROUND OF THE INVENTION

An agricultural seeding machine such as a row crop planter or graindrill places seeds at a desired depth within a plurality of parallelseed trenches formed in soil. In the case of a row crop planter, aplurality of row crop units is typically ground driven using wheels,shafts, sprockets, transfer cases, chains and the like or powered byelectric or hydraulic motors. Each row crop unit has a frame which ismovably coupled with a tool bar. The frame may carry a main seed hopper,herbicide hopper and insecticide hopper. If a herbicide and insecticideare used, the metering mechanisms associated with dispensing thegranular product into the seed trench are relatively simple. On theother hand, the mechanisms necessary to properly meter the seeds, anddispense the seeds at predetermined relative locations within the seedtrench are relatively complicated.

The mechanisms associated with metering and placing the seeds generallycan be divided into a seed metering system and a seed placement systemwhich are in series communication with each other. The seed meteringsystem receives the seeds in a bulk manner from the seed hopper carriedby the planter frame or by the row unit. Different types of seedmetering systems may be used, such as seed plates, finger plates, seeddisks, etc. In the case of a seed disk metering system a seed disk isformed with a plurality of seed cells spaced about the periphery of thedisk. Seeds are moved into the seed cells with one or more seeds in eachseed cell depending upon the size and configuration of the seed cell. Avacuum or positive air pressure differential may be used in conjunctionwith the seed disk to assist in movement of the seeds into the seedcell. The seeds are singulated and discharged at a predetermined rate tothe seed placement or delivery system.

The most common seed delivery system may be categorized as a gravitydrop system. In the case of the gravity drop system, a seed tube has aninlet end which is positioned below the seed metering system. Thesingulated seeds from the seed metering system merely drop into the seedtube and fall via gravitational force from a discharge end thereof intothe seed trench. The seed tube may have a rearward curvature to reducebouncing of the seed as it strikes the bottom of the seed trench and toimpart a horizontal velocity to the seed in order to reduce the relativevelocity between the seed and the ground. Undesirable variation inresultant in-ground seed spacing can be attributed to differences in howindividual seeds exit the metering system and drop through the seedtube. The spacing variation is exacerbated by higher travel speedsthrough the field which amplifies the dynamic field conditions. Furtherseed spacing variations are caused by the inherent relative velocitydifference between the seeds and the soil as the seeding machine travelsthrough a field. This relative velocity difference causes individualseeds to bounce and tumble in somewhat random patterns as each seedcomes to rest in the trench.

Various attempts have been made to reduce the variation in seed spacingresulting from the gravity drop. U.S. Pat. No. 6,681,706 shows twoapproaches. One approach uses a belt with flights to transport the seedsfrom the meter to the ground while the other approach uses two belts togrip the seed and transport it from the meter to the ground. While theseapproaches control the seed path and reduce variability due to dynamicevents, neither approach seeks to deliver the seed with as small aspossible horizontal velocity difference relative to the ground. U.S.Pat. Nos. 6,651,57, 7,185,596 and 7,343,868 show a seed delivery systemusing a brush wheel near the ground to regulate the horizontal velocityand direction of the seed as it exits the seeding machine. However,there is still a gravity drop between the seed meter and the brush wheelwhich produces variation in seed spacing.

SUMMARY OF THE INVENTION

The present invention provides a seed delivery system that removes theseed from the seed meter by capturing the seed. The delivery system thenmoves the seed down to a lower discharge point and accelerates the seedrearward to a horizontal velocity approximately equal to the forwardtravel speed of the seeding machine such that the seed, when discharged,has a low or zero horizontal velocity relative to the ground. Rolling ofthe seed in the trench is reduced as a result of the near zerohorizontal velocity relative to the ground. Furthermore, as the seedexperiences a controlled descent from the point at which it is removedfrom the meter to a point very near the bottom of the trench, the systembecomes a nearly impervious to the field dynamics experienced by the rowunit. The combination of controlled descent and discharge at asubstantially zero horizontal speed relative to the ground reduces seedspacing variability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a planter having the seed delivery system ofthe present invention;

FIG. 2 is a side view of a row unit of the planter of FIG. 1;

FIG. 3 is an enlarged side view of the seed delivery system of thepresent invention;

FIG. 4 is a top view of a planter row unit showing the metering systemorientation in one alternative arrangement of the metering system anddelivery system of the present invention;

FIG. 5 is a top view similar to FIG. 4 illustrating the delivery systemwith the meter housing removed;

FIG. 6 is a side view of the row unit of FIG. 4;

FIG. 7 is a perspective view of the seed disk used in the seed metershown in FIGS. 4-6;

FIG. 8 is a sectional view along the line 8-8 of FIG. 7 illustrating theorientation of the seed disk and brush or the seed delivery system ofthe present invention;

FIG. 9 is a side view of a row unit showing the orientation of thedelivery system of the present invention and a vacuum belt seed meter;

FIG. 10 is a side view of another orientation of the seed deliverysystem of the invention with a vacuum belt seed meter; and

FIG. 11 is a side view illustrating the orientation of the seed deliverysystem of the invention with a finger pick-up meter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1 an example planter or seeding machine 10 isshown containing the seed delivery system of the present invention.Planter 10 includes a tool bar 12 as part of a planter frame 14. Mountedto the tool bar are multiple planting row units 16. Row units 16 aretypically identical for a given planter but there may be differences. Arow unit 16 is shown in greater detail in FIG. 2. The row unit 16 isprovided with a central frame member 20 having a pair of upwardlyextending arms 21 (FIG. 4) at the forward end thereof. The arms 21connect to a parallelogram linkage 22 for mounting the row unit 16 tothe tool bar 12 for up and down relative movement between the unit 16and toolbar 12 in a known manner. Seed is stored in seed hopper 24 andprovided to a seed meter 26. Seed meter 26 is of the type that uses avacuum disk as are well known to meter the seed. Other types of meterscan be used as well. From the seed meter 26 the seed is carried by adelivery system 28 into a planting furrow, or trench, formed in the soilby furrow openers 30. Gauge wheels 32 control the depth of the furrow.Closing wheels 34 close the furrow over the seed. The gauge wheels 32are mounted to the frame member 20 by arms 36. The toolbar and row unitare designed to be move over the ground in a forward working directionidentified by the arrow 38.

The row unit 16 further includes a chemical hopper 40, a row cleanerattachment 42 and a down force generator 44. The row unit 16 is shown asan example of the environment in which the delivery system of thepresent invention is used. The present invention can be used in any of avariety of planting machine types such as, but not limited to, row cropplanters, grain drills, air seeders, etc.

With reference to FIG. 3, the seed delivery system 28 is shown ingreater detail. Delivery system 28 includes a housing 48 positionedadjacent the seed disk 50 of the seed meter. The seed disk 50 is agenerally flat disk with a plurality of apertures 52 adjacent theperiphery of the disk. Seeds 56 are collected on the apertures from aseed pool and adhere to the disk by air pressure differential on theopposite sides of the disk 50 in a known manner. The disk may have aflat surface at the apertures 52 or have seed cells surrounding theapertures 52. The disk rotates clockwise as viewed in FIG. 3 as shown bythe arrow 54. At the top of FIG. 3, seeds 56 are shown adhered to thedisk.

The seed delivery system housing 48 has spaced apart front and rearwalls 49 and 51 and a side wall 53 therebetween. An upper opening 58 inthe housing side wall 53 admits the seed from the metering disk 50 intothe housing. A pair of pulleys 60, 62 are mounted inside the housing 48.The pulleys support a belt 64 for rotation within the housing. One ofthe pulleys is a drive pulley while the other is an idler pulley. Thebelt has a base member 66 to engage the pulleys and elongated bristles70 extending therefrom. The bristles are joined to the base member atproximal, or radially inner, ends of the bristles. Distal, or radiallyouter, ends 74 of the bristles touch, or are close to touching, theinner surface 76 of the housing side wall 53. A lower housing opening 78is formed in the side wall 53 and is positioned as close to the bottom80 of the seed trench as possible. As shown, the lower opening 78 isnear or below the soil surface 82 adjacent the trench. The housing sidewall forms an exit ramp 84 at the lower opening 78.

Returning attention to the upper portion of FIG. 3, a loading wheel 86is provided adjacent the upper opening 58. The loading wheel ispositioned on the opposite side of the seeds 56 from the brush 64 suchthat the path of the seeds on the disk brings the seeds into a nip 88formed between the loading wheel and the distal ends 74 of the bristles70. At the location of the nip 88, the air pressure differential acrossthe seed disk 50 is terminated, freeing the seed from the apertures 52in the disk. The bottom surface of the loading wheel, facing the seeddisk 50, has recesses 90 formed therein. The recesses 90 receive seedagitators 92 projecting from the seed disk 50. The moving agitators, byengagement with the recesses in the loading wheel, drive the loadingwheel in a clockwise rotation.

In operation, the belt 64 is rotated in a counterclockwise direction. Asthe belt curves around the pulleys, the bristles will naturally open,that is, separate from one another as the distal ends of the bristlestravel a larger circumferential distance around the pulleys than theinner ends of the bristle at the belt base member. This produces twobeneficial effects as described below. The seeds are transferred fromthe seed meter to the delivery system as the seeds are brought by thedisk into the nip 88. There the seeds are pinched off the seed diskbetween the loading wheel and the bristles 70 to remove the seed fromthe seed disk and seed meter. The seeds are captured or entrapped in thebristles by insertion of the seed into the bristles in a radialdirection, that is from the ends of the bristles in a direction parallelto the bristle length. This occurs just as the belt path around thepulley 60 ends, when the bristle ends are closing back together uponthemselves, allowing the bristles to close upon, and capture the seedstherein. As the belt continues to move, the bristles move or convey theseeds downward to the housing lower opening. The side wall 53 of thehousing cooperates with the bristles 70 to hold the seed in the brushbristles as the seed is moved to the lower opening.

The lower opening 78 and the ramp 84 are positioned along the curvedbelt path around the pulley 62. The bristle distal ends thus cause thelinear speed of the seeds to accelerate relative to the speed of thebelt base member 66 and the housing as shown by the two arrows 94 and96. The seeds are then propelled by the bristles over the ramp 84 anddischarged through the lower opening 78 into the seed trench. The angleof the ramp 84 can be selected to produce the desired relationshipbetween the seed vertical and horizontal speeds at discharge. Theforward travel direction of the row unit is to the left in FIG. 3 asshown by the arrow 38. At the discharge, the horizontal speed of theseed relative to the ground is minimized to reduce roll of the seed inthe trench.

The belt shown in FIG. 3 has relatively long bristles. As a result ofthe long bristles and the seed loading point being at the end of thecurved path of the brush around the pulley 60 results in the seeds beingloaded into the belt while the bristles have slowed down in speed. Thebristle speed at loading is thus slower than the bristle speed at thedischarge opening as the belt travels around the pulley 62. This allowsin the seed to be loaded into the belt at a relatively lower speed whilethe seed is discharged at the lower end at a desired higher speed. Asdescribed above, it is preferred that the horizontal velocity of theseed at the discharge be equal to the forward travel speed of theplanter but in the rearward direction such that the horizontal velocityof the seed relative to the ground is close to or equal to zero. Thelong bristles can be used to increase the speed of the seed as ittravels around the pulley. However, a short bristle brush can be used aswell. With a short bristle brush, there will be little acceleration inthe speed of the seed as the seed travels around the pulleys. The beltwill have to be driven at a speed to produce the desired horizontalvelocity of the seed at the discharge. Even with a short bristle brush,the seed is still accelerated in the horizontal direction. As the belttravels around the pulley, the direction of travel of the seed changesfrom the predominantly vertical direction, when the seed is moveddownward from the seed meter, to a predominantly horizontal direction atthe discharge. This produces an acceleration of the seed velocity in thehorizontal direction.

With the delivery system 28, the seed is captured by the delivery systemto remove the seed from the seed meter. The seed is then moved by thedelivery system to the seed discharge point where the seed isaccelerated in a rearward horizontal direction relative to the housing.From the seed meter to the discharge, the seed travel is controlled bythe delivery system, thus maintaining the seed spacing relative to oneanother.

In the embodiment shown in FIG. 3, the seed disk and the front and rearwalls 49, 51 of the housing 48 lie in planes that are generally parallelone another. As shown, the plane of the delivery system is generallyparallel to the direction of travel of the row unit. Other relationshipsbetween the seed meter and delivery system are shown and describedbelow.

As shown in FIG. 3, the side wall 53 is divided by the upper and loweropenings 58, 78 into two segments, 53 a and 53 b. Segment 53 a isbetween the upper and lower openings in the direction of belt travelwhile the segment 53 b is between the lower and upper openings in thedirection of belt travel. It is the gaps in the side wall 53 that formthe upper and lower openings. It should be understood, however, that thedelivery system will function without the segment 53 b of the side wall.It is only the segment 53 a that functions together with the beltbristles to deliver the seed from the meter to the seed trench. Thus,the term “upper opening” shall be construed to mean an open area beforethe side wall segment 53 a in the direction of belt travel and the term“lower opening” shall mean an open area after the side wall segment 53 ain the direction of belt travel.

With reference to FIGS. 4-7, the delivery system 28 is shown incombination with the seed meter and row unit structure in an alternativearrangement of the seed meter and delivery system 28. The seed meter 200is shown mounted to the row unit with the seed disk 202 in a verticalorientation but at an angle to the forward travel direction shown by thearrow 38. FIG. 4 shows of the seed meter orientation in the row unitwithout the delivery system 28. The seed meter includes a housing havingtwo halves 204 and 206 releasable joined together in a known manner. Theseed meter is driven through a transmission 208 coupled to a drivecable, not shown.

In FIG. 5 only the seed disk 202 of the meter is shown with the seeddelivery system 28. As previously mentioned, the seed disk 202 is in avertical orientation but it does not lie in a plane parallel to theforward direction 38. Instead, the meter is oriented such that the diskis at a 60° angle relative to the forward direction when viewed fromabove. The seed of delivery system 28 is generally identical to thatshown in FIG. 3 and is driven by a motor 65. The delivery system,including of the brush belt 64, is generally vertical and aligned withthe fore and aft direction of the planter such that the angle betweenthe brush and the seed disk is approximately 60°. The angle between thedelivery system and a seed disk produces a partial “cross feed” of theseed into the brush. That is, the seed is fed into the brush at an angleto the lengthwise direction of the bristles. This is in contrast to FIG.3 where the seed enters the brush in a direction substantially parallelto the lengthwise direction of the brush bristles. If the brush and seeddisk were oriented at 90° to one another, a total cross feed would beproduced with seed entering the brush perpendicular to the bristles.

The seed disk 202 is shown enlarged in FIGS. 7 and 8. The disk 202 hasopposite sides, a vacuum side 216 and seed side 218. The seed side 218has a surface 219 near the periphery that defines a reference plane. Thereference plane will be used to describe the features of the disk nearthe disk periphery. An outer peripheral lip 220 is recessed from thereference plane. The peripheral lip 220 creates a radially outward edgeface 222. A circumferential row of spaced apart apertures 224 isarranged around a circular path radially inward of the edge face 222.Each aperture extends through the disk between the vacuum side 216 andthe seed side 218. Radially inward of each aperture 224, there is aradially elongated recess 226. The recess 226 is recessed axially intothe disk from the reference plane. In operation, the disk rotates in acounterclockwise direction as indicated by the arrow 228. Duringrotation, the recesses 226 agitate the seed in the seed pool.

Surrounding each aperture 224 is a tapered recess, or shallow seed cell,232 that extends axially into the disk from the reference plane. Seedcell 232 begins at a leading edge 234 in the direction of rotation ofthe disk and is progressively deeper into the seed side 218 to atrailing edge formed by an axially projecting wall 236. The taperedrecess or seed cell 232 reduces the vacuum needed to pick-up and retainseed in the apertures 224. The seed cell also enables the seed to sitlower relative to the seed side 218 of the disk, allowing the seed to beretained while the seed singulator removes doubles or multiples of seedfrom the apertures 224. In addition, the recess wall 236 agitates seedin the seed pool, further aiding in seed pick-up. The wall 236 extendslengthwise in a predominately radial direction as shown by the dashedline 238. The walls 236, while predominately radial, are inclined to theradial direction such that the inner end of the wall 236 is leading theouter end of the wall in the direction of rotation. Immediatelyfollowing each wall 236, as the disk rotates, is a projection, orupstanding peg, 240 extending axially from the disk seed side. The pegsengage seed in the seed pool for agitation to aide in seed pick-up. Thepegs 240 are located slightly radially inward of the circular path ofapertures 224 to avoid interference with the seed singulator.

With reference to FIG. 8, the disk 202 is shown in operation and inposition relative to the belt 64 in the delivery system 28. As seeds 244are carried by the disk 202 into the bristles of the brush 64, the wall236 and the pegs 240 act to push the seed 244 into the bristles of thebrush 64 and assist in keeping the seed from being knocked off the diskupon the seed's initial contact with the brush bristles. Once the seedis inserted into the brush bristles, the vacuum from the opposite sideof the disk is cut-off, allowing the brush to sweep the seed off thedisk in a predominately radial direction relative to the disk. An insert246 overlies the lip 220 at the point of seed release to hold the seedin the brush bristles in the transition between the disk and the sidewall 53 (FIG. 3) of the delivery system housing. The disk 202 isinclined to the length of the brush bristles at approximately a 60degree angle. This produces the partial cross-feed of the seed into thebrush bristles.

FIG. 9 shows the brush belt seed delivery system 28 in combination witha vacuum belt metering system having a metering belt 302. The vacuumbelt meter is fully described in co-pending U.S. patent application Ser.No. 12/363,968, now issued U.S. Pat. No. 7,918,168, and incorporatedherein by reference. The belt 302 picks-up seed at a pick-up region 304at a lower, front location of the belt's path and transports it to thedelivery system at a release region 306 at an upper, rear location ofthe belt's path. In this arrangement of the belt meter and the brushdelivery system, the delivery system is again partially cross fed withseeds from the meter.

Another arrangement of the delivery system together with a vacuum meterbelt is shown in FIG. 10. The delivery system 28 is in-line with thebelt meter 124. This allows the distal ends of the brush bristles tosweep over the surface of the metering belt 126 to capture the seedtherefrom. The meter belt 126 is wrapped around pulleys 128. Themetering belt 124 is similar and functions as the belt 302 mentionedabove.

The delivery system of the present invention can also be used with seedmeters other than air pressure differential meters. For example, withreference to FIG. 11, a finger pick-up meter 130 is shown, such as thatdescribed in U.S. Pat. No. 3,552,601 and incorporated herein byreference. Seed is ejected from the meter through an opening 132. Thedelivery system 134 has a brush belt 136 wrapped about pulleys 138 and140. As shown, the belt pulley 138 shares a common drive shaft withfinger pick-up meter 130. A hub transmission such as a sphericalcontinuously variable transmission or a three speed hub can be used todrive the belt 136 at a different speed from the meter 130. The deliverysystem housing includes a side wall 142. A ramp 146 is formed at thelower end of the wall 142 adjacent the lower opening 148. At the upperend of the delivery system, the upper opening is formed in the housingrear wall adjacent the opening 132 through which seeds are ejected fromthe seed meter. The seeds are inserted laterally into the brush bristlesin a complete cross-feed. As in the other embodiments, the seed iscaptured in the brush bristles, moved downward to the lower opening,accelerated rearward and discharged through the lower opening 148.

The endless member of the delivery system has been described as being abrush belt with bristles. In a broad sense, the bristles form an outerperiphery of contiguous disjoint surfaces that engage and grip the seed.While brush bristles are the preferred embodiment, and may be natural orsynthetic, other material types can be used to grip the seed such as afoam pad, expanded foam pad, mesh pad or fiber pad.

Having described the preferred embodiment, it will become apparent thatvarious modifications can be made without departing from the scope ofthe invention as defined in the accompanying claims.

The invention claimed is:
 1. A seeding machine, comprising: a seedmetering system; a seed transfer device positioned adjacent to the seedmetering system; a seed delivery system comprising a housing having afirst opening and a second opening, the first opening located proximalto the seed transfer device through which seed is transferred from theseed metering system into the seed delivery system, and the secondopening located distal of the seed transfer device through which seed isdischarged from the seed delivery system; and an endless member of theseed delivery system movable within the housing to receive the seed atthe first opening and transport the seed to the second opening; whereinthe seed transfer device transfers seed from the seed metering system tothe seed delivery system through the first opening of the seed deliverysystem.
 2. The seeding machine of claim 1, wherein the housing comprisesan elongated side wall that defines the first and second openings. 3.The seeding machine of claim 1, wherein the first opening is defined inan upper portion of the housing and the second opening is defined in alower portion of the housing.
 4. The seeding machine of claim 1, whereinthe housing forms a ramp at the second opening along which the seed isdischarged from the seed delivery system.
 5. The seeding machine ofclaim 4, wherein the seed is transported by the endless member in adirection from the first opening to the second opening substantiallyperpendicular to the ramp formed at the second opening.
 6. The seedingmachine of claim 1, wherein the seed transfer device comprises a wheel.7. The seeding machine of claim 1, wherein the seed transfer device isrotatable about a first axis and the seed metering system is rotatableabout a second axis, the first and second axes being offset from butparallel to one another.
 8. The seeding machine of claim 1, wherein theseed metering system comprises a seed metering disk that is rotatableabout a first axis in a first rotational direction, the seed transferdevice is rotatable about a second axis in a second rotationaldirection, and the endless member moves about at least one pulley whichis rotatable about a third axis in a third rotational direction, whereinthe first and second rotational directions are the same but opposite ofthe third rotational direction.
 9. The seeding machine of claim 8,wherein the first axis, the second axis and the third axis are offsetfrom but parallel to one another.
 10. The seeding machine of claim 8,wherein the first axis and the third axis are not parallel to oneanother.
 11. The seeding machine of claim 1, wherein the endless membercomprises a belt that is rotatably driven by at least one pulley. 12.The seeding machine of claim 1, wherein the seed transfer devicecomprises a surface that contacts the seed and directs the seed throughthe first opening onto the endless member.
 13. The seeding machine ofclaim 1, wherein the seed metering system comprises a plurality ofapertures through which an air differential is applied for maintainingseed thereon, the seed metering system being movable to convey seed tothe seed transfer device.
 14. The seeding machine of claim 1, whereinthe seed travels along a seed path defined between the seed meteringsystem and the second opening of the seed delivery system, wherein theseed transfer device is located upstream of the first opening along theseed path.
 15. The seeding machine of claim 14, wherein the seedtransfer device is positioned along the seed path between the seedmetering system and the endless member.
 16. The seeding machine of claim1, wherein the endless member travels about a first curved path at anupper portion of the housing and about a second curved path at a lowerportion of the housing, wherein the first opening is positioned alongthe first curved path and the second opening is positioned along thesecond curved path.
 17. A row unit of a planter configured to move in atravel direction while planting seed, comprising: a seed hopper forholding a plurality of seeds; a seed metering system including a seedmetering device for receiving seed from the seed hopper; a seed deliverysystem comprising a housing defining a first opening and a secondopening, the first opening located proximal to the seed metering systemthrough which seed is transferred into the seed delivery system, and thesecond opening located distal of the seed metering system through whichseed is discharged from the seed delivery system for planting in afurrow; an endless member of the seed delivery system movable within thehousing to receive the seed at the first opening and transport the seedto the second opening; and a seed transfer device disposed adjacent tothe first opening for transferring seed from the seed metering system tothe seed delivery system through the first opening of the seed deliverysystem.
 18. The row unit of claim 17, wherein: the housing comprises anelongated side wall that defines the first opening in an upper portionof the housing and the second opening in a lower portion of the housing;and the housing forms a ramp at the second opening along which the seedis discharged from the seed delivery system in a direction substantiallyopposite of the travel direction.
 19. The row unit of claim 17, wherein:the seed metering system comprises a disk having a plurality ofapertures through which an air differential is applied for maintainingseed thereon, the disk being rotatable to transport seed to the seedtransfer device; and the seed transfer device comprises a rotatablewheel for transferring seed from one of the plurality of aperturesthrough the first opening to the endless member.
 20. The row unit ofclaim 17, wherein: the seed transfer device comprises a wheel rotatableabout a first axis; and the seed metering system is rotatable about asecond axis, the first and second axes being offset from but parallel toone another.